Urea-containing (meth)acrylic acid derivatives of triisocyanates-compositions for an artificial tooth

ABSTRACT

For filling and forming teeth, novel (meth)acrylic acid derivatives of triisocyanates of the formula ##STR1## wherein R 1  and R 2  are identical or different and stand for hydrogen or a lower alkyl radical, 
     R 3 , R 4  and R 5  are identical or different and denote hydrogen or methyl, 
     y 1  to y 3  are identical or different and denote divalent straight-chain or branched hydrocarbon radicals of 2 to 15 carbon atoms which may optionally include 1 to 3 oxygen bridges and which may be unsubstituted or substituted by 1 to 4 additional (meth)acryloyloxy radicals, 
     X 1  to X 3  are identical or different and denote --NR 1  -- or --O--, at least one of the radicals X 1  to X 3  denoting --NR 1  --, and the rings 
     A and B are identical or different and may be aromatic or saturated.

This is a division of application Ser. No. 620,228, filed Nov. 20, 1990,now pending, which is division of application Ser. No. 517,261, filedMay 1, 1990, now U.S. Pat. No. 5,008,436.

The invention relates to novel urea group-containing acrylic acid andmethacrylic acid derivatives of triisocyanates, referred to subsequentlyas (meth)acrylic acid derivatives, and to the preparation thereof. Thenovel compounds may be employed as monomers for use in dentistry.

Novel urea group-containing (meth)acrylic acid derivatives oftriisocyanates of the formula ##STR2## have been found; in this formulaR¹ and R² are identical or different and stand for hydrogen or a loweralkyl radical,

R³, R⁴ and R⁵ are identical or different and denote hydrogen or methyl,

Y¹ to Y³ are identical or different and denote divalent straight-chainor branched hydrocarbon radicals of 2 to 15 carbon atoms which mayoptionally include 1 to 3 oxygen bridges and which may be unsubstitutedor substituted by 1 to 4 additional (meth)acryloyloxy radicals,

X¹ to X³ are identical or different and denote --NR¹ -- or --O--, atleast one of the radicals

X¹ to X³ denoting --NR¹ --, R¹ having the meaning defined above, and therings

A and B are identical or different and may be aromatic or saturated.

The (meth)acrylic acid derivatives may be pure isomers or a mixture ofisomers. For the use according to the invention of the (meth)acrylicacid derivatives in dental materials, it is particularly advantageous toemploy mixtures of isomers and derivatives, since they have a lowerviscosity than compositions consisting of pure isomers.

Within the scope of the present invention, the substituents maygenerally have the following meanings:

Lower alkyl can denote a straight-chain or branched hydrocarbon radicalof 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. The followinglower alkyl radicals may be cited as examples: methyl, ethyl, propyl,isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl and isohexyl.

The divalent hydrocarbon radicals Y¹ to Y³ can denote straight-chain orbranched aliphatic hydrocarbon radicals of 2 to 15 carbon atoms,preferably 2 to 10 carbon atoms. Each of the radicals Y¹ to Y³ mayoptionally include 1 to 3 oxygen bridges, preferably 1 or 2 oxygenbridges. The radicals Y¹ to Y³ may also be substituted by 1 to 4,preferably 1 or 2 (meth)acryloyloxy radicals. The following radicals maybe cited as examples: ##STR3##

The ring A stands for a benzene nucleus or a cyclohexane radical whichcarries two or three substituents. The ring B stands for a benzenenucleus or a cyclohexane radical which carries three or foursubstituents.

The novel (meth)acrylic acid derivatives are colorless and of lowvolatility, and after polymerization give rise to transparent plasticsof high wear resistance.

They are particularly suitable for use in dental materials, such asdental filling compounds and coatings. The materials obtained in thismanner are distinguished by a surprisingly high resistance to physicaland chemical stresses. Compared with conventional materials used forthis purpose, they are considerably harder and more fracture-resistant.

U.S. Pat. No. 4,868,325 discloses (meth)acrylic acid derivatives oftriisocyanates which contain exclusively urethane groups as the bridgingmember between the (meth)acrylate and triisocyanate units. Thesecompounds have essentially three crucial drawbacks which make their usemore difficult. Their viscosity is so high that they have to be mixedwith large amounts of comonomers which impair the properties of thecured polymers. Their preparation requires prolonged reaction times,exceeding one day. In addition, their preparation takes place in alow-boiling, inert solvent which has to be exchanged for comonomers inan additional processing stage.

All three problems could be resolved with the aid of the ureagroups-containing (meth)acrylic acid derivatives of triisocyanatesaccording to the invention in that these can be prepared directly inadmixture with suitable comonomers in distinctly shorter reaction timesin the form of low-viscosity oils, which in view of the usuallyincreased tendency of urea derivatives to crystallization wassurprising.

Preferred compounds are (meth)acrylic acid derivatives according to theinvention of the formula I ##STR4## wherein R¹ stands for hydrogen,

R² stands for hydrogen or an alkyl radical of 1 to 4 carbon atoms,

R³, R⁴ and R⁵ are identical or different and denote hydrogen or methyl,

Y¹ to Y³ are identical or different and denotes divalent straight-chainor branched aliphatic hydrocarbon radicals of 2 to 10 carbon atoms whichmay optionally include 1 or 2 oxygen bridges and which may beunsubstituted or substituted by 1 to 2 additional (meth)acryloyloxyradicals,

X¹ stands for --O--,

X² and X³ denote --NR¹ --,

the ring B is aromatic or saturated and the ring A is saturated.

Particularly preferred are (meth)acrylic acid derivatives of theformula: ##STR5## wherein R¹ stands for hydrogen,

R² stands for hydrogen or methyl,

R³, R⁴ and R⁵ are identical or different and denote hydrogen or methyl,

Y¹ to Y³ are identical or different and denote divalent straight-chainor branched aliphatic hydrocarbon radicals of 2 to 10 carbon atoms whichmay optionally include 1 or 2 oxygen bridges and which may beunsubstituted or substituted by 1 or 2 additional (meth)acryloyloxyradicals,

X¹ and X² stand for --O--,

X³ denotes --NR¹ --,

and the rings A and B are saturated.

The following (meth)acrylic acid derivatives are cited as examples:##STR6##

A method for the preparation of the (meth)acrylic acid derivativesaccording to the invention has been found which is characterized in thata triisocyanate of the formula II ##STR7## wherein R¹ and R² areidentical or different and stand for hydrogen or a lower alkyl radical,and the rings

A and B are identical or different and may be aromatic or saturated,

is reacted with aminoalkyl (meth)acrylates of the formula ##STR8## and,optionally, with hydroxyalkyl (meth)acrylates of the formula ##STR9##wherein R³, R⁴ and R⁵ are identical or different and denote hydrogen andmethyl,

Y¹ to Y³ are identical or different and denote divalent straight-chainor branched hydrocarbon radicals of 2 to 15 carbon atoms which mayoptionally include 1 to 3 oxygen bridges and which may be unsubstitutedor substituted by 1 to 4 additional (meth)acryloyloxy radicals, and

R¹ has the meaning defined above.

Triisocyanates of the formula II are known (U.S. Pat. No. 4,603,189,U.S. Pat. No. 4,675,437) and may be obtained by phosgenation of thecorresponding triamino compounds.

Hydroxyalkyl (meth)acrylates of the formula VI to VIII and aminoalkyl(meth)acrylates of the formula III to V are commercially available andmay be prepared in a known manner by partial esterification of thecorresponding polyols or by esterification of alkanolamines in thepresence or absence of protective groups for the amino function.

The process according to the invention is generally carried out in sucha manner that 0 to 0.8 equivalents, based on each isocyanate group ofthe triisocyanate (II), of a hydroxyalkyl (meth)acrylate of the formulaeVI, VII or VIII and 0.2 to 1.1 equivalents of an aminoalkyl(meth)acrylate of the formulae III, IV or V or a mixture of thecompounds III to VIII are employed, the total of all hydroxylequivalents per isocyanate group having to be 0 to 0.8 and the total ofall amino equivalents per isocyanate group having to be 0.2 to 1.1, insuch a proportion that the total of hydroxyl and amino equivalents perisocyanate group is 0.9 to 1.1.

Preferred processes are those in which 0.3 to 0.7 equivalents, based oneach hydroxyalkyl (meth)acrylate of the triisocyanate (II), of ahydroxyalkyl (meth)acrylate of the formulae VI, VII or VIII and 0.3 to0.7 equivalents of an aminoalkyl (meth)acrylate of the formulae III, IVor V or a mixture of the compounds III to VIII are employed, the totalof all hydroxyl equivalents and the total of all amino equivalentshaving to be in each case 0.3 to 0.7 in such a proportion that the totalof hydroxyl and amino equivalents per isocyanate group is 1.0 to 1.05.

The process according to the invention may be carried out in an inertsolvent with exclusion of water. Suitable examples are chloroform,tetrahydrofuran, acetone, dioxane, methylene chloride, toluene andacetonitrile. Preferred solvents are chloroform, toluene, acetone andmethylene chloride.

In particular, the process according to the invention may also takeplace in a reactive diluent which also contains (meth)acrylate groups,as solvent, and therefore need not be removed after the reaction, as itis copolymerizable with the compounds according to the invention. Thus,the resultant mixture of monomers is directly suitable for thepreparation of dental materials. Suitable reactive diluents aremonomethacrylates and dimethacrylates of dihydric alcohols such asalkanediols or ethylene glycols and propylene glycols of two to twelvecarbon atoms. Hexanediol dimethacrylate and triethylene glycoldimethacrylate, ethylene glycol dimethacrylate and neopentyl glycoldimethacrylate are particularly suitable.

The process according to the invention is generally carried out in atemperature range from 20° to 100° C., preferably 30° to 70° C.

The process according to the invention is generally carried out atnormal pressure. However, it is also possible to carry out the processin a pressure range from 1 to 15 bar.

The reaction of the isocyanate (II) according to the invention ispreferably carried out with exclusion of water (preferably less than0.1% of water).

In order to speed up the reaction, tin-containing catalysts such asdibutyltin-dilaurate, stannous octoate or dibutyltin dimethoxide arepreferably used.

It is also possible to use compounds comprising tertiary amino groups ortitanium compounds as catalysts. The following catalysts are cited asexamples: diazabicycle[2.2.2]octane, triethylamine, N-methylpiperidineand tetrabutoxytitanium (Ullmann, Encyclopadie der technischen Chemie,vol. 19, p. 306 (1981)).

The catalyst is generally employed in an amount of 0.01 to 2.5% byweight, preferably of 0.1 to 1.5% by weight, based on the total amountof reactants.

The reaction is generally performed in the presence of 0.01 to 0.2% byweight of a polymerization inhibitor, for example2,6-di-tert.-butyl-4-methylphenol.

The process according to the invention may be carried out, for example,as follows:

The hydroxyalkyl (meth)acrylate (VI-VIII) is dissolved in a solvent andtreated first with the catalyst and then with the triisocyanate (II)with stirring. When all the hydroxyl functions have reacted (IR check,NCO titration), the aminoalkyl (meth)acrylate (III-V) is added dropwise.When the isocyanate groups have reacted completely, the reactionproducts are isolated by removal of the solvent. A preliminarypurification using adsorbents, for example activated carbon, fuller'searth, silica gel or aluminum oxide is of course also possible.

The (meth)acrylic acid derivatives of triisocyanates according to theinvention may also be employed as monomers for the preparation ofpolymeric materials. The polymerization may be carried out in a mannerknown per se by a radical initiation and gives rise to polymers with ahigh crosslinking density.

The (meth)acrylic acid derivatives of triisocyanates according to theinvention may be used particularly as monomers for dental materials.Examples of their use as dental material are dental filling compounds,dental coatings and components for the preparation of dentures.Depending on application, dental materials may contain other auxiliarysubstances.

For use as monomers for dental filling compounds, or coatings (dentallacquers) in dentistry, the (meth)acrylic acid derivatives oftriisocyanates according to the invention may be mixed with comonomersknown per se. For example, the viscosity may be adjusted to suit theapplication. These mixtures of monomers generally have a viscosity inthe range of 60 to 20.000 mPa.s.

The following comonomers may be cited as examples:

triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate,1,12-dodecanediol dimethacrylate, 1,6-hexanediol dimethacrylate,diethylene glycol dimethacrylate,2,2-bis[p-(2'-hydroxy-3'-methacryloyloxypropoxy)phenyl]propane,2,2-bis[p-(2'-methacryloyloxyethoxy)phenyl]propane. Comonomerscomprising urethan groups, for example the known reaction products of 1mol of a diisocyanate (for example hexamethylene diisocyanate,trimethylhexamethylene diisocyanate, isophorone diisocyanate) with 2mols of a hydroxyalkyl (meth)acrylate (for example glyceroldimethacrylate, 2-hydroxypropyl acrylate etc.) are also advantageous.

Further examples of comonomers are the following:

trimethylolpropane tri(meth)acrylate,bis(meth)acryloyloxyethoxymethyl)tricyclo[5.2.1.0².6 ]decane (accordingto U.S. Pat. Nos. 4,323,696 and 4,323,348),1,3-di((meth)acryloyloxypropyl)-1,1,3,3-tetramethyldisiloxane,1,3-bis(3-(meth)acryloyloxyethylcarbamoyloxypropyl)-1,1,3,3-tetramethyldisiloxane.Those comonomers which have a boiling point greater than 100° C. at 13mbar, are particularly preferred.

Within the scope of the present invention, it is likewise preferred touse mixtures of various (meth)acrylic acid derivatives according to theinvention.

The proportion of the urea group-containing (meth)acrylic acidderivatives of triisocyanates according to the invention in the mixturesof monomers is generally 10 to 90% by weight, preferably 20 to 75% byweight.

It is also possible to employ mixture of monomers which comprise severalcomonomers.

The urea group-containing (meth)acrylic acid derivatives oftriisocyanates according to the invention, optionally in admixture withthe cited monomers, may be cured by methods known per se to yieldcrosslinked polymers (G. M. Brauer, H. Argentar, Am. Chem. Soc., Symp.Ser. 212, pp. 359-371 (1983)). A system consisting of a peroxidiccompound and a reducing agent, for example based on tertiary aromaticamines, is suitable for the so-called redox polymerization. Examples ofperoxides are:

dibenzoyl peroxide, dilauroyl peroxide and di-4-chlorobenzoyl peroxide.

Examples of suitable tertiary aromatic amines areN,N-dimethyl-p-toluidine, bis(2-hydroxyethyl)p-toluidine,bis(2-hydroxyethyl)-3,5-dimethylaniline andN-methyl-N-(2-methylcarbamoyloxypropyl)-3,5-dimethylaniline disclosed inDE-A 2,759,239.

The concentration of the peroxide and of the amine should preferably bechosen such that it is 0.1 to 5% by weight, preferably 0.5 to 3% byweight, based on the mixture of monomers. The mixtures of monomerscontaining peroxides and those containing amines are stored separatelyuntil used.

However, the monomers according to the invention may be also caused topolymerize by irradiation with UV light or visible light (for example inthe wavelength range of 230 to 650 nm). Examples of suitable initiatorsfor the photo-initiated polymerization are benzil, benzil dimethylketal, benzoin monoalkyl ether, benzophenone, p-methoxybenzophenone,fluorenone, thioxanthone, phenanthraquinone and 2,3-bornanedione(camphorquinone), in the presence or absence of synergistically actingphotoactivators, such as N,N-dimethylaminoethyl methacrylate,triethanolamine and 4-N,N-dimethylaminobenzenesulphonic acidbisallylamide.

The photopolymerization process is carried out, for example, asdisclosed in DE-A 3,135,115.

In addition to the initiators described above, light stabilizers andpolymerization inhibitors known per se for this purpose may be added.

The light stabilizer and the polymerization inhibitor are added to eachcase generally in an amount of 0.01 to 0.50 parts by weight, based on100 parts by weight of the mixture of monomers. The mixtures of monomersmay be used as dental coatings (dental lacquers) without the addition offillers. A scratch-resistant coating is obtained on the substrate afterthe polymerization.

Fillers are generally added to mixtures of monomers for use as dentalfilling compounds. Mixtures of monomers of a viscosity in the range from60 to 20.000 mPa.s are particularly suitable for achieving a high degreeof filling. Inorganic fillers may preferably be added to the mixtures ofmonomers comprising the compounds of the formula I. Examples of theseare rock crystal, quartzite, kristobalite, quartz glass, highly dispersesilicic acid, aluminum oxide and glass ceramics, for example glassceramics containing lanthanum and zirconium (U.S. Pat. No. 3,973,972).

To improve their attachment to the polymer matrix of thepolymethacrylate, the inorganic fillers are preferably pretreated with acoupling agent. The coupling may be affected, for example, by treatmentwith organosilicone compounds (E. P. Plueffemann, Progress in OrganicCoatings, 11, 297 to 308 (1983)).3-Methacryloyloxypropyltrimethoxysilane is used for preference.

The fillers for use in the dental filling compounds according to theinvention generally possess an average particle diameter of 0.01 to 100μm, preferably 0.05 to 50 μm, particularly preferably 0.05 to 5 μm. Itmay also be advantageous to employ by side several fillers each of whichpossesses a different particle diameter and a different degree ofsilanization.

The proportion of fillers in the dental filling compounds is generally 5to 85% by weight, preferably 50 to 80% by weight.

To prepare the dental filling compounds, the components are processedwith the aid of commercial kneaders.

The proportion of the (meth)acrylic acid derivatives according to theinvention in the filling compounds is generally 5 to 90% by weight,preferably 10 to 60% by weight based on the filling compound. Curing ofthe dental filling compounds to a molding takes place in the cavity ofthe tooth, when the methods defined above are used. Because of the highwear resistance of the resultant dental filling, dental fillingcompounds which comprise the compounds according to the invention inpolymerized form are particularly suitable for use in ancillarydentistry.

The (meth)acrylic acid derivatives of triisocyanates according to theinvention may also be employed as components in the production ofdentures.

For this purpose, the monomers according to the invention are combinedwith components known per se, used in the customary manner. The monomersare preferably used in admixture with alkyl methacrylates, such asmethyl methacrylate. Bead polymers known per se may be addedadditionally. For the adjustment of the color of the tooth, knowninorganic and organic colored pigments and opacifiers are used. The useof stabilizers and light stabilizers is likewise possible.

The artificial teeth are produced by radical polymerization of thedental compounds with appropriate shaping. Processing can take placefollowing an injection process as well as a stamping process and isgenerally carried out by production methods customary for teeth based onpolymethyl methacrylate, for example by heat polymerization in thepresence of polymerization initiators known per se, for example thosebased on peroxides and azo compounds, such as dibenzoyl peroxide,dilauroyl peroxide, cyclohexyl percarbonate and azoisobutyrodinitrile.Mixtures of polymerization initiators of different half-life periods inrespect to their decomposition are likewise highly suitable.

EXAMPLES 1-4 Preparation of adducts from triisocyanates, hydroxyalkyl(meth)acrylates and aminoalkyl (meth)acrylates

The following abbreviations are used in the test below:

GDMA: glycerol dimethacrylate (an isomeric mixture of 1,3- and1,2-bismethacryloyloxypropanol)

HDMA: hexanedioldimethacrylate (1,6-bismethacryloyloxyhexane)

HEMA: 2-hydroxyethylmethacrylate (2-methacryloyloxyethanol)

BAEMA: N-tert-butylaminoethyl methacrylate(N-tert-butyl-N-2-methacryloyloxyethylamine)

Triisocyanate: triisocyanatodicyclohexylmethane (an isomeric mixturewith an NCO content of 41.5% by weight)

M-triisocyanate: triisocyanotocyclohexylmethylcyclohexylmethane (anisomeric mixture with an NCO content of 38.2% by weight)

Stabilizer: 2,6-di-tert-butyl-4-methylphenol

Catalyst: Stannous octoate

General procedure for the preparation of the (meth)acrylic acidderivatives according to the invention

To a mixture of HDMA, GDMA, stabilizer and catalyst, stirred at 30° C.,feed No. 1 (triisocyanate, M-triisocyanate) is added dropwise, thereaction mixture is heated to 55° C. and stirred at this temperatureuntil the GDMA is completely consumed. Feed No. 2 comprising a furtherhydroxyalkyl (meth)acrylate (for example HEMA) is then added and thereaction mixture is again stirred at constant temperature until thisalcohol component has completely reacted as well. Feed No. 3 comprisingan aminoalkyl (meth)acrylate (for example BAEMA) is then added dropwiseand the reaction mixture is then stirred at 55° C. until all isocyanategroups have been completely consumed. A colorless mixture of monomers isobtained which may be used directly for the production of dentalmaterials.

                                      TABLE 1                                     __________________________________________________________________________    The amounts used according to the general procedure (all data are in g        (mol))                                                                                Ex. 1    Ex. 2    Ex. 3     Ex. 4                                     __________________________________________________________________________    Initial mix:                                                                  HDMA    90.19 (0.355)                                                                          96.14 (0.355)                                                                          100.0  (0.393)                                                                          191.39 (0.735)                            GDMA    54.73 (0.240)                                                                          54.73 (0.240)                                                                          109.45 (0.480)                                                                          109.45 (0.480)                            Stabilizer                                                                             0.36 (0.002)                                                                           0.38 (0.002)                                                                           0.26 (0.001)                                                                            0.37 (0.002)                             Catalyst                                                                               0.12     0.12     0.12      0.12                                     Feed No. 1:                                                                   Triisocyanate                        72.91 (0.720NCO)                         M-triisocyanate                                                                       79.35 (0.721NCO)                                                                       79.35 (0.721NCO)                                                                        79.35 (0.721NCO)                                   Feed No. 2:                                                                           31.25 (0.240)                                                                            --       --        --                                      HEMA                                                                          Feed No. 3:                                                                           45.12 (0.243)                                                                          90.24 (0.487)                                                                           45.12 (0.243)                                                                           45.12 (0.245)                            BAEMA                                                                         __________________________________________________________________________

EXAMPLE 5

The procedure of Example 3 is followed, except that the reactive diluentHDMA is replaced by 150 ml of chloroform.

At the end of the reaction the chloroform is removed in vacuo and theadduct according to the invention of M-triisocyanate, GDMA and BAEMA isobtained in the form of a colorless oil.

IR (film): γ=3360, 2920, 1720, 1640, 1519, 1450, 1320, 1298, 1158, 1007,942, 812, 752 cm⁻¹.

¹ H-NMR (CDCl₃, 360 MHz): δ=1.38 (s, 3H, cyclohexyl-CH₃), 0.9-1.6 (m,20H, CH-- and CH₂ of the dicyclohexylmethane unit), 1.4 (s, 9H,C(CH₃)₃), 1.93 (bs, 15H, COCCH₃), 3.4 (m, 2H, NCH₂), 4.3 (m, 10H, OCH₂),5.3 (m, 2H, O--CH), 5.6, 6.12 (2m, 5H in each case, vinyl --H) ppm.

¹³ C-NMR (CDCl₃, 90 MHz): δ=18.3, 28.7, 29.4 (CH₃), approx. 30 (C of thedicyclohexylmethane unit), 43.2 (NCH₂), 55.9 (C(CH₃)₃), 62.7 (OCH₂),69.5 (O--CH), 126.2 (═CH₂), 135.8 (═CCH₃), 155.0 (O--CO--NH), 158.5(N--CO--N), 166.7 (O--CO--C) ppm.

EXAMPLE 6

0.2% by weight of camphorquinone and 0.5% by weight of4-N,N-dimethylaminobenzenesulphonic acid bisallylamide are added to themixture of monomers from Example 3 consisting of 70% by weight of theadduct of M-triisocyanate, GDMA and BAEMA and of 30% by weight of HDMA,and the mixture is processed in the absence of light to yield anactivated mixture of monomers. This mixture is cured by visible light ata 60 sec. exposure to give rise to a plastic of high mechanicalstability, which may be used as sealing material in dentistry (sealer,liner, dental lacquer).

For the preparation of a dental filling compound, 25 parts by weight ofthe activated mixture of monomers and 75 parts by weight of a mixture ofpyrogenic silicic acid and ground quartz glasses, silanized with3-methacryloyloxypropyltrimethoxysilane, is processed to a paste in acommercial kneader at room temperature. A test sample cured according toDIN 13,922 with the aid of a commercial dental lamp (Translux®),produced from this paste, possesses, in addition to a high flexuralmodulus and a high bending strength, in particular a high abrasionresistance.

It is understood that the specification and examples are illustrativebut not limitative of the present invention and that other embodimentswithin the spirit and scope of the invention will suggest themselves tothose skilled in the art.

We claim:
 1. An artificial tooth formed of a composition comprising a(meth)acrylic acid derivative of a triisocyanate of the formula##STR10## wherein R¹ and R² are identical or different and stand forhydrogen or a lower alkyl radical,R³, R⁴ and R⁵ are identical ordifferent and denote hydrogen or methyl, Y¹ to Y³ are identical ordifferent and denote divalent straight-chain or branched hydrocarbonradicals of 2 to 15 carbon atoms which may optionally include 1 to 3oxygen bridges and which may be unsubstituted or substituted by 1 to 4additional (meth)acryloyloxy radicals, X¹ to X³ are identical ordifferent and denote --NR¹ -- or --O--, at least one of the radicals X¹to X³ denoting --NR¹ --, and the rings A and B are identical ordifferent and may be aromatic or saturated.
 2. An artificial tooth of atriisocyanate according to claim 1, whereinR¹ stands for hydrogen, R²stands for hydrogen or alkyl radical of 1 to 4 carbon atoms, R³, R⁴ andR⁵ are identical or different and denote hydrogen or methyl, Y¹ to Y³are identical or different and denote divalent straight-chain orbranched aliphatic hydrocarbon radicals of 2 to 10 carbon atoms whichmay optionally include 1 or 2 oxygen bridges and which may beunsubstituted or substituted by 1 or 2 additional (meth)acryloyloxyradicals, X¹ stands for --O--, X² and X³ denote --NR¹ --, the ring B isaromatic or saturated and the ring A is saturated.
 3. An artificialtooth of a triisocyanate according to claim 1, whereinR¹ stands forhydrogen, R² stands for hydrogen or methyl, R³, R⁴ and R⁵ are identicalor different and denote hydrogen or methyl, Y¹ to Y³ are identical ordifferent and denote divalent straight-chain or branched aliphatichydrocarbon radicals of 2 to 10 carbon atoms which may optionallyinclude 1 or 2 oxygen bridges and which may be unsubstituted orsubstituted by 1 or 2 additional (meth)acryloyloxy radicals, X¹ and X²stand for --O--, X³ denotes NR¹, and the rings A and B are saturated. 4.An artificial tooth according to claim 1, formed of the followingmonomers in approximately the indicated molar amounts:

    ______________________________________                                        HDMA                 0.355                                                    GDMA                 0.240                                                    M-triisocyanate      0.721 NCO                                                HEMA                 0.240                                                    BAEMA                0.243                                                    ______________________________________                                    


5. An artificial tooth according to claim 1, formed of the followingmonomers in approximately the indicated molar amounts:

    ______________________________________                                        HDMA                 0.355                                                    GDMA                 0.240                                                    M-triisocyanate      0.721 NCO                                                BAEMA                0.487                                                    ______________________________________                                    


6. An artificial tooth according to claim 1, formed of the followingmonomers in approximately the indicated molar amounts:

    ______________________________________                                        HDMA                 0.393                                                    GDMA                 0.480                                                    M-triisocyanate      0.721 NCO                                                BAEMA                0.243                                                    ______________________________________                                    


7. An artificial tooth according to claim 1, formed of the followingmonomers in approximately the indicated molar amounts:

    ______________________________________                                        HDMA                 0.735                                                    GDMA                 0.480                                                    Triisocyanate        0.720 NCO                                                BAEMA                0.245                                                    ______________________________________                                    


8. An artificial tooth according to claim 1, formed of the followingmonomers in approximately the indicated molar amounts:

    ______________________________________                                               GDMA            0.393                                                         M-triisocyanate 0.221                                                         BAEMA           0.243                                                  ______________________________________                                    


9. In the filling of a tooth or the formation of a tooth wherein apolymerizable derivatives if applied and polymerized, the improvementwherein such derivatives is a derivative according to claim 1.